Impedance Pumping in the Cardiovascular System

Moshe Rosenfeld, Fluid Mechanics and Heat Transfer, Faculty of Engineering,
Tel Aviv University

The research is focused on the investigation and implementation of impedance pump in cardiovascular applications. Impedance pumps offer a promising new technique for producing or amplifying a net flow without using valves, seals, rotating parts, making the impedance pump a strong candidate for biological implementations, such as in the vascular system.

The impedance pump is basically a combination of fluid filled connected tubes with different elastic properties. By pinching the flexible part of the pump periodically at an asymmetric position relative to the stiff ends, a net flow can be generated. In the present study, we aim first to simulate the flow in the elastic part to gain insight into the physical processes.

For this reason, an axisymmetric model was build, consisting of a straight elastic tube that was pinched by a flat pincher and was connected to rigid tubes at both edges. The domain of calculation included the elastic walls and the fluid region. The “pincher” was simulated by a contact surface with prescribed displacement.

The figure above shows the velocity vector field at three phases of the cycle, revealing asymmetric elastic waves that were found to drive the flow. The time history of the flow-rate for a pinching frequency of 4Hz and a tube diameter of 25mm is shown in the next figure. A net flow of about 6 l/min was obtained.